The invention relates to a liquid pump, in particular, a detergent liquid pump for household appliances and to a method for assembling such a pump.
The starting point for the subject matter of the invention are detergent liquid pumps such as those disclosed by German publication DE 90 16 330 U and German Published, Non-Prosecuted Patent Application DE 38 18 532 A1. As xe2x80x9cwet-rotorxe2x80x9d pumps, such detergent liquid pumps have a split cage or tube, within which a rotor, preferably, a permanently excited rotor, is rotatably mounted and has a wound stator assembly radially on the outside. In the prior art type of pump, the split cage/tube, which is preferably configured as a pot-shaped casing, merges at its pot-rim end into a flange that forms the base of a pump chamber and to which a pump casing can be connected with a seal in between. The rotor shaft is mounted rotatably in a bearing holder that can be fixed at the pot-rim end in the split cage, and one end of the rotor shaft, which carries a pump impeller, projects into the pump casing.
It is accordingly an object of the invention to provide a liquid pump, in particular, a detergent liquid pump for household appliances that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type and that reduces the effort involved in manufacturing and assembling a liquid pump of this kind while providing a high degree of adaptability to the requirements of specific customers.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a liquid pump, including a permanently excited rotor, a split cage having an outside and an axial end and defining an interior accommodating the permanently excited rotor, a stator, preferably, a wound stator assembly, radially situated on the outside of the split cage, a pump impeller, a rotor shaft having a shaft end, and a pump casing defining a casing interior accommodating the pump impeller on the shaft end. The pump casing is connected to the axial end of the split cage, and the pump casing and the split cage are retained together through an axial plug fit. The pump casing and the stator are retained together through an axial plug-fit. Preferably, the liquid pump is a detergent liquid pump for household appliances to be driven by a single-phase synchronous motor having a permanently magnetic rotor.
To reduce the effort involved in manufacture and assembly while providing a high degree of adaptability to the requirements of specific customers, the pump can be assembled on the modular principle by a technique involving mutual axial plug-in assembly at least between the split cage, together with the rotor mounted rotatably therein, and the pump casing and between the stator assembly or the cap accommodating the assembly and the pump casing. For noise deadening and sealing, a flexible intermediate supporting part, in particular an O-ring, is accommodated as a press fit at least in the plug-in joint between the split cage and the pump casing.
Given the construction of the liquid pump according to the invention, the most important modular components of the split cage or tube, with its bearing holders, of the pump casing and of the stator assembly or cap accommodating the stator assembly can be fitted in a particularly simple manner in the direction of the drive end from the non-drive end, at which the split cage is open and is readily accessible. The assembly is performed simply with plug-in or snap joints, without using screw fixings and fixing welds. If appropriate, the pump can be disassembled and replaced during testing or when damaged. At the same time, the stator assembly can be fixed advantageously without supporting loads relative to the split cage by virtue of its plug-in fit on the pump casing. According to a refinement of the invention, only an easy sliding fit involving mutual alignment is provided.
In accordance with another feature of the invention, there is provided a cap defining a cap interior accommodating the stator, and the stator and the pump casing are retained together through an indirect plug-fit.
In accordance with a further feature of the invention, the split cage and the cap or the stator are connected by a sliding and/or guiding fit free of significant radial supporting loads.
In accordance with an added feature of the invention, the split cage is pot-shaped and has a base, and the shaft end is a drive end projecting through the base into the pump casing and receiving the pump impeller.
In accordance with an additional feature of the invention, the pump impeller has a holder and the rotor shaft is inserted axially into the holder.
In accordance with yet another feature of the invention, the rotor shaft has a non-drive shaft end, the split cage has a non-drive cage end, and including a bearing holder holding the non-drive shaft end, the bearing holder being retained on the non-drive cage end in an axial plug-fit.
In accordance with yet a further feature of the invention, the liquid pump is configured to selectively assemble the split cage in an axial-plug fit with the pump casing from the non-drive shaft end, at least one of the stator and the cap receiving the stator in an axial-plug fit with the pump casing, the rotor shaft in an axial-plug fit with the pump impeller supported from the shaft end, and the non-drive end bearing holder in an axial-plug fit with the split cage.
In accordance with yet an added feature of the invention, the cap is to be configured by a user for matching user-specific requirements, particularly, connection and installation specifications, and otherwise has a universal motor component configuration.
In accordance with yet an additional feature of the invention, the split cage has plug-in holders, the stator has plug-in holders, the cap has plug-in holders, and the pump casing has a motor side. A radial flange is disposed at the motor side. An integrally formed axially projecting plug-in sleeve and plug-in holders mate corresponding ones of the plug-in holders of the split cage, the plug-in holders of the stator, and the plug-in holders of the cap.
In accordance with again another feature of the invention, there are provided a bearing holder holding the non-drive shaft end, the bearing holder being retained on the non-drive cage end in an axial plug-fit, and at least one flexible intermediate supporting part in a region of a mutual plug-fit retention between the split cage and the pump casing and between the bearing holder and the split cage.
In accordance with again a further feature of the invention, the at least one flexible intermediate supporting part is at least one flexible, elastomeric, intermediate supporting part.
By virtue of the flexible, in particular, elastomeric, intermediate supporting parts between the individual components to be connected by plug-fit retention, in particular, the split cage with the pump casing and the non-drive-end bearing holder with the split cage, it is possible, on one hand, to compensate for tolerances and avoid or compensate for mutual misalignment, to ensure a high degree of leaktightness against the escape of liquid from the pump casing or, where relevant, from the rotor chamber of the split cage and, at the same time, to achieve particularly low noise levels through the damping of vibration at the rotor or the windings.
In accordance with again an added feature of the invention, the at least one flexible, elastomeric, intermediate supporting part is at least one O-ring.
In accordance with again an additional feature of the invention, the at least one flexible intermediate supporting part is form-lockingly fixed relative to a respective pair of the split cage, the pump casing, and the bearing holder.
In accordance with still another feature of the invention, the form lock is at least one of a mutual snap connection and a latching connection.
In accordance with still a further feature of the invention, the at least one flexible intermediate supporting part is integrated.
In accordance with still an added feature of the invention, the pump casing has motor side and is divided axially into a pump-casing top part and a pump-casing bottom part, the pump-casing top part is disposed on the motor side; and the pump-casing bottom part faces away from the motor side and is connected to the pump-casing top part.
In accordance with still additional features of the invention, the pump-casing top part has an integral pressure branch and the pump-casing bottom part has an integral intake branch.
In accordance with still a further feature of the invention, the pump-casing bottom part is to be configured by a user, and the pump-casing top part has a universal motor component configuration.
With the objects of the invention in view, there is also provided a method for assembling a liquid pump including providing a liquid pump having a permanently excited rotor, a pot-shaped split cage having an outside, a drive end, and a non-drive end and defining an interior accommodating the permanently excited rotor, a wound stator assembly to be radially situated on the outside of the split cage, a pump impeller, a rotor shaft having a drive end, and a pump casing having a pump-casing top part, a pump-casing bottom part, a flange part, and a plug-in holder, the pump casing defining a casing interior accommodating the pump impeller on the shaft end, and the pump-casing top part having a plug-in holder. A drive-end bearing, preferably, a journal bearing, is axially pressed into a drive-end bearing holder at the drive end of the split cage from the non-drive end. Flexible intermediate supporting parts, preferably, O-rings, are mounted on the drive end of the split cage. The rotor is axially inserted into the split cage from the non-drive end. The drive end of the split cage is axially pressed into the plug-in holder of the pump casing for retaining the split cage at the pump casing and the drive end of the rotor shaft is simultaneously pressed into the pump impeller. The pump impeller is supported from the drive end of the rotor shaft in the pump-casing top part. A flexible intermediate supporting part is mounted on a non-drive-end bearing holder prefitted with a bearing, preferably a journal bearing. The non-drive-end bearing holder is axially pressed into the split cage from the non-drive end. A cap together with the wound stator assembly are axially mounted onto the plug-in holder of the pump-casing top part in a direction from the non-drive end of the split cage for retaining the stator at the pump casing and bringing the cap and the stator assembly to bear on the flange part. The pump-casing bottom part is connected to the pump-casing top part, preferably with a pump-casing seal in between.
Other features that are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a liquid pump, in particular, detergent liquid pump for household appliances, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.